Data events, such as events that trigger changes to a database, may be processed with stateless stream operators and state-based window operators. Each event identifies one or more sets of operators that operate on the data in one or more rows of a database. Conventionally, a first system may be used to process events with stateless stream operators and a second system may process events with state-based operators. Thus, a plurality of systems may need to be implemented and maintained to process events using both stateless stream operators and state-based window operators.